T&S windows usually have pretty dumb logic - a print at the current bid is a sell (red), and a print at the current offer is a buy (green). This is way off the way how modern ECNs/exchanges report trades and quotes. For almost all of them, trades are delays, so you really need to figure out what was going on in the past. The way I read the tape is that my application tries to deduce every print by looking at quotes back and tries to see whether it was a buy or sell (NYSE tape).

Here is an example: all T&S windows in the world will show you a 200 buy print here, whether in fact it was a sell order (on a minus tick offer).